Ship propulsion.



W. L. R. :ZMMET.

SHW [:RGPULSlON. Armenian man APR. 5. me.

1,270,13f1. PatentedJune 18, 191&

Fig. 2.

Inventor. Wiiiiam LREmmet,

His Attornegg.

UNITED STATES PATENT OFFICE.

WI$4LIAM L. R. EMMET, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SHIP PROPULSION.

Application filed April 5, 1916.

ments in Ship Propulsion, of which the following is a specification.

My invention relates to ship propulsion and particularly to systems or ship propulsion in which the propellers are driven by electric motors. The object oi? the inven' tion is generally the provision of certain improvements in propelling equipments for vessels, and more particularly the provision of an improved electric propelling equipment and especially an improved electric equipment in which the propellers are driven by alternating current electric motors. Other objects of the invention will be brought out in the course of the following description.

Nhen ships, having screws on both sides which are operated by separate turbinesor engines, are steered by movements of the rudder, every movement of the rudder tends to cause a variation in the relative propeller speeds of the two sides, the propellers on the concave side of the turning curve slowing down and those on the convex side speeding up. It by suitable. steam admission the engines on the two sides of the ship are held at equal speeds, the load on the en glue which drives a propeller on the concave side of the turning curve will become greater than tha on the convex side and the aggregate load on both engines will exceed that experienced with the same propeller speed with the helm amidships. Experiments with twin screw engine-driven battleships having large low speed propellers have shown that the variations of load under such conditions are very large, and that such variations of load between propellers may cause serious dilliculties in equipments in which the propellers are driven by alternating current motors supplied with electric energy from the same generator. For purposes of explanation I will take the case of an equipment having propeller-driving induction motors-connected to the same generator. Such motors nor? Specification of Letters Patent.

Patented June 18. 1918.

Serial No. 89,018.

mally operate nearly in synohronism with the generator and can only deliver their maximum torques when near to synchronism; f the maximum torque of a propeller-dri ing motor is exceeded by the demand on the propeller, the motor will drop out of step, that is, it will all away from a speed nearly synchronous with the gen orator and will stop or operate at some lower speed, thus drawing a very large current from the generator and exerting a small torque upon the propeller. Such dropping out of step of a propeller-driving motor on either side of the ship is in practice very objectionable and might seriously hamper the control of the ship during the interval of time necessary to again establish the proper speed relations between the motors and generator' Such reestablishment of the speed relations will generally call for intelligent actior iv the men handling the propelling machinery and since this might not be forthcoming in such an emer cncy, it is extreu'iely desirable to pro vide automatic means by which the steering of the ship cannot impose such excess torque upon any of the propeller-(hiviug motors.

The principal aim of my present invention is, accordingly, the provision of suitable means for minin'iiziug the objectionable effects on the propelling equipment which result from a substantial difference in load between propellers on opposite sides of the ship. In other words, the aim of my present invention is to overcome any objec tionable disturbances in the propelling equipment when the direction of thcships motion is altered. In carrying out the invention I provide means for limiting or do creasing the admission of elastic fluid o the prime mover of the propelling apparatus upon the occurrence of a substantial differ ence in load between propellers on opposite csides of the ship, and in another aspect-of the invention I provide means for limiting or decreasing the admission of elastic fluid to the'prime mover when the direction of the ships motion is altered. Thus, in its broadest aspect my present invention consists in limitingthe amount of power that can. be supplied top opeller's on opposite v tea i'bine for aim setting f vfiilzillisin by he operating 7 1 mit is siigzhtiy ibove the adiili cm 'iespmiding (0 that set mesh" L? v the iii-ziwijiigs EliQY-(HIVIDQ; amps/site and 31 ar'i C(HLZIQ 33, i'espectimiy.

supp from quarter ge ierzitor 00h. Lu is 211;. ei

The

n dies i in (EH-Gil of the 111i use .i'elitimis. I? c phase system .5. 0011140 ne indeisiwd that my iiiveiitimi is eqiiai: ilpjliiijiili", 0 any otii ci' po ypiizii e 'P 'urbine 35 s emiti'o motor k main mat r V a the curre sup ii-ed to the main motors bgco" e unequal, current will flow in the ciri the motor proportional to the, -mce in $111.; currents of a3 a main motors ft the motor carries a pinion hid"; meshes with a gear 4:7. The gear sii ably mounted on a t'irnbuckie 4 8, s0 11235 the iurnimckie can slide axially m the turnbuckle spiral a and secured to w. fixed pin @1 51 {xiii secnrk ii; the shaft of The spring is wmuid up ion (J'i the motm. 4-5 upon he 5? and it. the iii-aim by m 21m W of {ZUJLBH} in HS -ci "cuiis. and the spring further enemies in return Hie motor to an i 51011 when the motor (y owetad aiti is lewi M I, Cue in gowrning :iin the usual i9 if:

'2 king speed limit 0:?

REQQ 0 their imci; l or normal +9 can be arranged with an we Sui :1 iess 102d on ing a prime mover, a 'opeller, on each side of the ship adapted to he driven hy power developed by said prime mover, an adjustable speed governing mechanism for approximately maintaining any normal operating cps of said prime mover, and means able speed governing mechanism for approximately maintaining any normal operating speed of said prime mover, and means responsive to a change in the distribution of load between said propellers resulting from a change in the direction of motion of the ship for adjusting said speed governing mechanism for a lower speed limit.

7. A system of ship propulsion comprising a prime mover, a source of motive fluid for said prime mover, a propeller on each side of the ship adapted to be driven by power developed by said prime mover, an adjustable speed governing mechanisi'n for approximately maintaining any normal operating speed of said prime mover, and means for decreasing the supply of motive fluid to said prime mover upon a changein the direction of motion of the ship.

8. A system of ship propulsion comprising an elastic fluid turbine, an electric generator coupled to said turbine. a propeller on each side of the ship, an electric motor coupled to eachpropeller and adapted to be electrically connected to each generator, an adjustable speed governing mechanism for approximately maintaining any normal operating speed of said turbine, and means for" adjusting said speed governing meclianism for a lower speed limit upon a change in the direction of motion of the ship.

A s stem of ship propulsion coming a prime mover, a source of motive cold for said prime mover, an electric generator coupled to said prime mover,

propel! on each side of the ship, an eleccoupled to each propeller and to be electrically connected to said :SPODSlVG to a subload between the the supply l d to said prime mover, a 1 each side t .e ship, an alterhating: c pollen adapt" Mg, 1

to he electrically conicra'ivcr, an adjustable mechanism approxia, normal operating :cnt motor coupled to each pro speed of said prime mover, and means responsive to a substantial difference in load between the motors on the two sides of the ship for adjusting said speed governing mechanism for a lower speed limit.

1].. 1r .ing a prime mover, an electric generate r coupled to said prime mover, a propeller on each side of the ship, an electric motor coupled to each propeller and adapted to be electrically connected to said generator, an adjustable speed governing mechanism for approximately maintaining any normal operating speed of said prime mover, electrodynainic means responsive to a predetermined unbalancing oi the currents supplied to said motors by said generator, and means operatively connecting said electrodynamic means to said speed governing mechanism.

12. A system of ship propulsion comprising an elastic fluid turbine, an alternating current generator coupled to said turbine, a propeller on each side of the ship, an alternating current motor coupled to each propeller and adapted to be electrically connected to said generator, an adjustable speed governing mechanism for approximately maintaining any normal operating speed of said turbine, an auxiliary electric circuit electrically associated with said m0- tors and adapted to carr" a current upon the occurrence of a predetermined unbalancing of the currents supplied to said motors by said generator, and electrodynamic means in cluded in said auxiliary circuit and opera tively connected to said speed governing mechanism.

A system of ship propulsion comprising a prime mover, a source of motive fluid for said prime mover, a propeller on each side or": the ship adapted to be driven by power developed by said. prime i'nove'r, an adjustable speed over-hing mechanism for approximately 1 ntaining any normal operating speed or said prime mover, and means associated with said speed governing mechanism for preventing an increased admission of motive fluid to said prime mover to meet an increased load on either of said propellers when the direction of the ships motion is altered.

l-l. A system of ship propulsion comprising a prime mover, a source of motive fluid for said prime mover, a propeller on each side of the ship adapted to be driven by power developed 7 id ir'rno mover, an adjustable speed gov rninp; mechanism for ziproximatoly mainta ning normal opeii. speed of said pri mover, and means for preventing an increased admisof motive fluid to said prime mover to v F p x I meet an increased lewd on Gil/161 of said ro ellers when the direction the shins. i i L stem of ship propulsion compris- 

